A capacitive sensor can sense a position of an input approaching a sensing area of a sensing device by detecting changes of a capacitive signal, so it is widely used in touch input devices, such as in various touch displays.
An important key component of the capacitive sensor is an array of sensor electrodes, which correspondingly is the sensing area; when an input object (e.g. a finger) is approaching the array of sensor electrodes, the capacitive signal at the corresponding position changes, thereby sensing the position or even action of the input object on the sensing area.
As for a mutual-capacitance capacitive sensor, for example, its array of sensor electrodes comprises transmitter electrodes and receiver electrodes arranged in rows and columns, wherein traces are provided on the transmitter electrodes for electrically connecting to a processing device of the capacitive sensor, so that a certain signal can be biased on the transmitter electrodes through the traces. For example, in practical application, transmitter electrodes of the array of sensor electrodes are scanned row by row (i.e. biasing the signal row by row) and changes of the regular coupling capacitance are detected.
Sensitivity and accuracy/linearity of sensing of the capacitive sensor is a constant pursuit in the industry at present, wherein the pattern and arrangement of electrodes of the array of sensor electrodes have significant influence to the sensing accuracy. But the irregular (or undesirable) coupling capacitance generated in the array of sensor electrodes is liable to negatively affect such performance as accuracy/linearity of the capacitor sensor.